A new design of polarization prism system is described, which has many advantages, including low loss, high isolation, compact construction and convenient adjustment. Its loss and isolation are 0.6 dB and 24 dB respectively. By using this system, it was experimentally confirmed that the insertion loss, including fiber connection loss and the isolation of the circulator at 1.3 μm are 2.2～2.4 dB and 20.5～23.1 dB, respectively.